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CarbonXtreme . Midland Helicopters . HeliProz

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Gasser Model RC Helicopters > Predator Gasser build
 
 
jschenck
Elite Veteran
Location: La Vista, NE.

I plan to have my main gear/bearing assembly apart this weekend. I'll post pix on how I install these o-rings. After talkng with Bill and reading the results that abwombak posted it should really help. My understanding is the up/down play in the bearing assembly allows the whole bearing asembly to get cocked sideways a bit in there causing everything to get out of alinment. This causes drag on the system and that is also why my main gear was rubbing on the frame creating quite a bit of "white dust". The O-rings support the spraq bearings while still giving them a little room to float which is needed. The cocked bearing assembly causes all kinds of problems including small amplitude vibrations resonating through the frame killing bearings, swash, etc... also the extra drag causes the engine to run harder thus hotter. Sounds like this has been a suble problem that Bill finally nailed down.

I hope Bill or someone else will correct me if I'm off here.

...yep...
05-03-2008 04:45 AM
 
 
AceBird
Elite Veteran
Location: Utica, NY USA

Quote 
BTW Acebird, your fan looks a lot different than mine, is that because mine would be the NX upgrade?

I have no idea. What does the NX upgrade look like?

Ace
What could be more fun?
05-03-2008 01:21 PM
HOMEPAGE  
 
 
AceBird
Elite Veteran
Location: Utica, NY USA

Quote 
My understanding is the up/down play in the bearing assembly allows the whole bearing asembly to get cocked sideways a bit in there causing everything to get out of alinment.

If the spur gears are aligned properly with the correct mesh the gear cannot cock regardless of how much up and down freedom it has. If the spur gears are not aligned or at the proper mesh you have found the root cause of the vibration and clutch slip. The o-rigns may dampen the vibration but they are a band aide to a problem that shouldn't exist.

Just as a side note if your gears are noisy it implies something wrong in the mesh or alignment. Pretty much a hard fasten rule for any gear train.

Ace
What could be more fun?
05-03-2008 01:35 PM
HOMEPAGE  
 
 
pgkevet
Heliman
Location: surrey UK

If I may paoch your thad for a mo' Profwiz,

Dialing for psychiatric care

SO I have the top surface of the fan down to negligible runout. I have the outside of the fan down to negligible runout. I have the inside of the fan hub topsides down to negligible except one quadrant..and finally realise that there's a burnish inside which implies that its the inside that thas been worn by my testing with the clutching in that isolated quadrant!

OK so fan fitted.

How the devil can you make any real sense of the clutch shoe. I have that dialed to negligible topside..but that's meaningess if I had the engine or cluch happily angled by luck to be horizonal.

Outside runout way off. BUT The outside of the clutch isn't circular anyway!!! AAAgghhh. So the best i can see possible is to bolt it up to even runout (albeit different values) across 2 opposite poles??? (N-S and E-W).

Pass the Valium

And I still can't figure out how I happened to align the engine in vice and the dial indicator so that the topside has no runout...

And thanks to this forum.. Or I'd have torn my hair out wondering hy M3 bolts don't fit in M4 holes...

pgk
05-03-2008 06:13 PM
 
 
Professorwiz
Veteran
Location: Livonia, Michigan - USA

No problem on the poach,
You indicate the 2 solid sides. If the inside is good and the fit of the clutch is good all should be good. I struggled for 3 hours getting mine to .0015". I'm not very happy but it's withing tolerance. I will be making my own in the future, like Acebird did. Spending a little time on making that part concentric, and a little tighter tolerance should make a huge difference.. That and I think blue would be prettier..

Russ

Go that way really fast.. If something gets in your way.. TURN
05-03-2008 08:59 PM
HOMEPAGE  
 
 
pgkevet
Heliman
Location: surrey UK

<<I struggled for 3 hours getting mine to .0015">>

Only 3 hrs? I'm thinking of pulling it all and starting again, again...

You talking making a blue fan or a blue clutch or a blue bell? assuming bell??.. How about 2? .. since it happens that I've got a few other blue bits ordered..

.had to take a break and fix up my 450 from today's minor prang (sorta took a corner too fast, too low..).. nice sunny weather but windy..

pgk
05-03-2008 09:54 PM
 
 
Professorwiz
Veteran
Location: Livonia, Michigan - USA

Have you gotten to putting the rubber on the frame sides yet.. OMG! What a pain in the fingers. I couldn't imagine doing this in another 10 years..

Russ

Go that way really fast.. If something gets in your way.. TURN
05-04-2008 04:51 AM
HOMEPAGE  
 
 
jschenck
Elite Veteran
Location: La Vista, NE.

Quote 
If the spur gears are not aligned or at the proper mesh you have found the root cause of the vibration and clutch slip. The o-rigns may dampen the vibration but they are a band aide to a problem that shouldn't exist.

Just as a side note if your gears are noisy it implies something wrong in the mesh or alignment. Pretty much a hard fasten rule for any gear train.

exactly - btw, I did note out loud that when I was shooting auto's it sounded like a turbine coming down with the gear noise.

...yep...
05-04-2008 06:09 AM
 
 
pgkevet
Heliman
Location: surrey UK

<<Have you gotten to putting the rubber on the frame sides yet.. OMG! What a pain in the fingers. I couldn't imagine doing this in another 10 years>>

I'll let you know ... I've now spent/wasted over 6hrs on this fan/hub ..and gonna have to accept the best I've got..

pgk
05-04-2008 08:05 AM
 
 
AceBird
Elite Veteran
Location: Utica, NY USA

Quote 
You indicate the 2 solid sides. If the inside is good and the fit of the clutch is good all should be good.

This is one of the accepted approaches but it is wrong. It only tells you the alignment in one plane. When it is 90 degrees from the solid part of the clutch it could be way off and I will bet it is.

Put a pin or a plug in the one way clutch and turn the pin so the clutch grabs. Now indicate the pin in all four quadrants. Any other method is a joke.



Ace
What could be more fun?
05-04-2008 01:35 PM
HOMEPAGE  
 
 
pgkevet
Heliman
Location: surrey UK

<<Any other method is a joke>>

I'm sure the packers are still laughing too over the teasingly ocassion small number on a packet whose content don't necessarily quite relate to what you think. Or the amusement of giving me two identical pieces of u-shaped plastic to force around the tank hole.. so I did the big one first.. and ended up with a 1" gap.. and in case of my mistake.. took it off and found it fit perfectly on the other rim.... and the second piece is still 1" too short for the larger hole.

But let's not be downhearted...after the water-boarding and foot beatings this is only a little step up.. --We laugh at the challenge!!

I think I might even have found the correct m4 button-heads as well as the m3 I put aside.. but that's only after buying my own and cutting them down to size

nyone got a spare inch..apart from the offers I keep getting by email to gain same?

pgk
05-04-2008 03:12 PM
 
 
jschenck
Elite Veteran
Location: La Vista, NE.

Quote 

nyone got a spare inch

heh - don't need it

seriously, just make sure that the gap is in the middle of one of the sides, it'll be fine. I put the gap at the bottom and you can't see it.

...yep...
05-04-2008 03:46 PM
 
 
Professorwiz
Veteran
Location: Livonia, Michigan - USA

BTW, when bolting the fan shroud on, I noticed that the bolts are in the shroud from the factory, only they aren't the correct ones. The ones in the shroud are 12mm long, they really need to be 8mm. Also the rubber is 2 lengths. I put the wrong one on the wrong side.
Kinda hard to tell which one goes where so measure.. I cut the extra length of the one and put it on the other. It's about 1/2" difference..

Russ

Go that way really fast.. If something gets in your way.. TURN
05-04-2008 04:05 PM
HOMEPAGE  
 
 
pgkevet
Heliman
Location: surrey UK

Didn't measure shroud bolt length.. but they work and they're staying...did measure rubber lenghts against each other... exact same.

Could hve done with some spare.. didn't like the way the plug lead goes through that sharp carbon.. even filing the edges round... I'll be shoe-gooing something on there later..

Now gotta figure which upper frame carbon part is supposed to go which side.. all the pics in my guide and carbon upgrade guide don't show the two different upper frame part shapes I've got.. Got one with one servo hole above a switch? hole and other with two servo holes...

Got a new slogan - "Predator - If it was obvious it'd be easy"

or perhaps - "Why call it Predator? Ya gotta eat red meat to build one of these!"

I'll find some black wire sleeving to fill the frame rubber deficit..

pgk
05-04-2008 04:41 PM
 
 
Professorwiz
Veteran
Location: Livonia, Michigan - USA

Yeah I'm not excitied about the way the plug wire would rub on the carbon fiber frame either. Perhaps a rubber clamp or something would be good there. Even stainless brade would wear out on the CF after a while.

Russ

Go that way really fast.. If something gets in your way.. TURN
05-04-2008 04:43 PM
HOMEPAGE  
 
 
pgkevet
Heliman
Location: surrey UK

I was planning on splitting a short lenth of polyprop tubing and shoe-goo on such edges.. just tend to trim my fingertips splitting it neatly

pgk
05-04-2008 04:55 PM
 
 
AceBird
Elite Veteran
Location: Utica, NY USA

Quote 
Yeah I'm not excitied about the way the plug wire would rub on the carbon fiber frame either.

Move the coil to the side and keep the HT wire on the outside and you will be happier in the long run.



Ace
What could be more fun?
05-04-2008 05:50 PM
HOMEPAGE  
 
 
pgkevet
Heliman
Location: surrey UK

<<Move the coil to the side and keep the HT wire on the outside and you will be happier in the long run.>>

Makes sense..just need to scavenge bits..and take it apart again.

..Any idea re tank holes.. strikes me there outta be washers under these fittings nuts? Holes sizes for tight threads?

...And as for the comedian that tossed two long lengths of copper tube into my tank.... so I could have a happy-hour fishing them out...

..I assume they servo no purpose beyond an amusing game??

pgk
05-04-2008 06:27 PM
 
 
AceBird
Elite Veteran
Location: Utica, NY USA

Quote 
And as for the comedian that tossed two long lengths of copper tube into my tank....

If you have access to medical staff at a hospital there is a host of grabber devices that work superbe. The simple hemostats are good enough and cheap if not medical rated.



Ace
What could be more fun?
05-04-2008 11:27 PM
HOMEPAGE  
 
 
jschenck
Elite Veteran
Location: La Vista, NE.

copper tubing in the tank is becaue this is the same tank the glow powered pred uses, they didn't pack the tanks different for glow and gas AFAIK.

Check out these pix for a guide to putting frame together. Take note the rear (elevator) servo goes on the LEFT side frame which is different than the aluminum frame where it goes on the right side. Make sure that the rear elevator pivot is flipped over to accommodate this. Also they call for CA glueing the elevator pivot bearings into the frame, wish I hadn't done that. Now I'll never be able to replace them. Maybe a bit of hot glue gun glue if you are really worried about them slipping, but I doubt they'll move even just 'popping' them in there.



...yep...
05-05-2008 03:36 AM
 
 
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Gasser Model RC Helicopters > Predator Gasser build
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